It looks like the VDSL link is whats limiting your speed. (Maximum 13 Mb/s down 4,46 Mb/s up) This could be because you are a over i Km from the node or poor quality cable. It could also be due to phones or other devices plugged into spare phone sockets or gateway not plugged directly into phone socket. (Remove ADSL filter/splitter).
It is not paying for the speed boost if you can't locate and fix the cause of the low VDSL link speed.